A scintillating fiber detector for muon beam profile measurements in high magnetic fields

A position-sensitive detector (the Muon Beam Profile Monitor— μ BPM) for non-relativistic muon beams and to be used in high magnetic fields was developed. The μ BPM consists of a grid of 20 scintillating fibers probing the muon beam intensity along the horizontal (x) and the vertical (y) directions perpendicular to the beam direction (z), i.e., at x i and y j coordinates of the fibers ( i , j = 1 … 10 ). The readout of the fibers is realized by novel avalanche microchannel photodiodes (AMPDs). The use of AMPDs results in a compact design of the device, its insensitivity to magnetic fields, and the ability to handle high event rates. The μ BPM was successfully utilized in the measurement of the muon beam profiles in magnetic fields up to 4.8 T.